On Tuesday 12 April 2005 10:51, Duncan wrote: > Pascal BERTIN posted <[EMAIL PROTECTED]>, excerpted below, > on Tue, 12 Apr 2005 10:17:52 +0200: > Besides, -Os /shouldn't/ create issues, as the only stuff activated by > any of the -Ox options are known to be generally safe, or they wouldn't > be activated at least on that arch, for a -Ox option, in the first > place. The GCC devs don't put the dangerous stuff in the -Ox options, > you must enable it with specific flags. Further, it's pretty much -O2, > minus the size-expanding stuff like unrolling loops and the like in the > first place, so if -O2 works, so /should/ -Os. At least that's the > theory. Of course, as complicated as compiling to machine code can be, > there are ways to break virtually anything if one is trying to do so, > or using known dangerous techniques. Still, I've seen no evidence of > such in regard to -Os in KDE 3.3 or 3.4, at least as compiled with GCC > 3.4.x.
You are a bit wrong here. The -Ox options do not enable features that should be expected to be dangerous. It does however enable features that are in some gcc versions buggy. As most distributions (the biggest compilers) in general compile their stuff with -O2 and rather generic architecture options those are the most widely tested options. sse floating point math has for example been broken in the whole 3.2.x gcc series. As the only architecture supporting this was the p4 architecture it was not very common and it did not occur either with all packages (and only those that use floating point calculations). In general there are many different combinations possible for gcc options and some of them only create bugs in interaction with eachother. This leads to the fact that gcc tends to be buggy with the lesser used (or newer) features. Paul -- Paul de Vrieze Gentoo Developer Mail: [EMAIL PROTECTED] Homepage: http://www.devrieze.net
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